In a combine harvester, crop is cut from a field and fed to a multistage crop processing system which acts to separate the grain from the straw and chaff. Ideally all the grain should be collected whole and stored in a tank while the straw and the chaff should be discharged from the back of the harvester.
To separate the grain from the remainder of the crop material, the crop is first fed to a threshing system which comprises a cylinder or drum that rotates along a concave. This separates the straw from the grain and chaff. In conventional combines the straw is carried to the back of the harvester by so-called straw walkers. In rotary type harvesters the cylinder is positioned generally lengthwise of the harvester and comprises a front threshing section and a rear separating section along which the straw is spiraled rearwardly. The threshed straw is discharged as a swath for subsequent baling or else it is chopped and spread evenly over the ground.
The grain is separated from the chaff by a cleaning system in which it tossed on sieves as a fan blows air over the sieves. The chaff is blown away while the grain drops through the sieves and is collected in a tray from which it is then transferred to a grain, tank by a suitable conveyor. Tailings, i.e. grain ears that comprise grain that has not been separated from the straw, fail to drop through the grain sieves and eventually drop instead onto a separate tray from which they are recycled through the threshing mechanism.
It is not believed necessary for an understanding of the present invention to describe the construction of a combine harvester in any greater detail but more information on the construction of combine harvesters can be obtained from numerous prior art references, such as U.S. Pat. No. 4,344,443.
In any design of combine harvester, there are several operating parameters of the crop processing system that will affect the harvesting quality. In particular, if the parameter settings are incorrect for the current crop and/or harvesting conditions, the grain kernels may be broken, the grain collected in the grain tank may contain too much material other than grain (known as MDG), there may be an excess of tailings discharged from the cleaning system and there may be reduced processing efficiency resulting in grain loss.
Parameters such as grain purity, grain breakage, tailings quantity and grain loss, which are herein referred to as “crop quality parameters”, can be measured by known sensors so that the operator may be warned of poor crop processing performance. However, conveying all the necessary information to the operator has resulted in ever more complex user interfaces making it difficult even for experienced operators to decide what to do when a warning is received that the crop processing is not operating optimally. This problem is exacerbated by the fact that harvesters are often driven by less skilled operators because of the shortage of skilled labour.